duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
For example, 25 to 30 percent of cases of retinoblastoma, a cancer of the eye that develops mainly in children, are caused by an inherited mutation in a gene called RB1 (7). However, retinoblastoma accounts for only about 3 percent of all cancers in children.